Goldman Sachs & Co., a unit of the most profitable bank in Wall Street history, took $15 billion from the U.S. Federal Reserve on Dec. 9, 2008, the biggest single loan from a lending program whose details have been secret until today.

The program, which peaked at $80 billion in loans outstanding, was known as the Fedâs single-tranche open-market operations, or ST OMO. It made 28-day loans to units of 19 banks between March 7, 2008, and Dec. 30, 2008. Bloomberg reported on ST OMO in May, after the Fed released incomplete records on the program. In response to a subsequent Freedom of Information Act request for details, the central bank disclosed borrower names, amounts borrowed and interest rates.

ST OMO is the last known Fed crisis lending program to have its details made public. The central bank resisted previous FOIA requests on emergency lending for more than two years, disclosing details in March of its oldest loan facility, the discount window, only after the U.S. Supreme Court ruled it had to. When Congress mandated the December 2010 release of data on special initiatives the Fed created in its unprecedented $3.5 trillion response to the 2007-2009 collapse in credit markets, ST OMO -- an expansion of a longstanding program -- wasnât included.

âThe Fed has come a long way over a long period of time as far as transparency,â said Raymond W. Stone, managing director and economist with Stone & McCarthy Research Associates in Princeton, New Jersey. âThey thought counterparties might be harmed, but now so much time has passed that the information is not as sensitive anymore.â